The present invention is directed to a hedge trimmer drive assembly of the type used to drive one or more reciprocating blades in a hedge trimmer.
A typical hedge trimmer may have a motor with a rotating drive shaft, a relatively small gear connected to the drive shaft, a relatively large gear in contact with and driven by the small gear, a gear box housing for enclosing the two gears, one or more reciprocating cutting blades, and means for interconnecting the large gear so as to reciprocatingly drive one or more of the cutting blades. A hedge trimmer of the above type is disclosed in U.S. Pat. No. 3,200,493 to Dodegge.
It may be advantageous to form the gear box housing from plastic to reduce the cost of manufacturing the hedge trimmer. However, the use of plastic for the internal housing(s) of the hedge trimmer presents a problem. During operation of a hedge trimmer, internal forces and/or shocks generated within the hedge trimmer tend to cause the two gears to become misaligned with respect to each other, particularly when the hedge trimmer blades become temporarily jammed due to the cutting of a relatively large branch, for example.
These forces and/or shocks, referred to herein as gear-separation forces, along with the heat generated within the hedge trimmer during normal operation, may cause the plastic gear box housing to deform to such an extent that the two gears within the gear box housing become disengaged, resulting in the hedge trimmer becoming inoperable. Even if the two gears do not become disengaged, misalignment of the gears may result in undue wear of the gears, thus limiting the operational life of the hedge trimmer.